Wave energy coupling device for ultrasonic energy



April 29, 1958 c, MENG 2,832,572

WAVE ENERGY COUPLING DEVICE FOR ULTRASONIC ENERGY Filed Dec. 1, 1955 2Sheets-Sheet 1 III " J. a K INVENTOR.

CARL. l M ENG BY 7 c ATTORNE C. L. MENG April 29, 1958 WAVE ENERGYCOUPLING DEVICE FOR ULTRASONIC ENERGY 2 Sheets-Sheet 2 Filed Dec.

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C A R L l M E N 6 III \00000 \O O O AT TORN E vs United States PatentWAVE ENERGY COUPLING DEVICE FOR ULTRASONIC ENERGY CarlL. Meng, Phoenix,Ariz.

Application December 1, 1955, Serial No. 550,233

6 Claims. (Cl. 259-1) An object of my invention is to provide a couplingdevice for ultrasonic energy and it consists in the constructions,operations and advantages hereinafter described and claimed.

The purpose of my invention is to provide a method of couplingultrasonic energy to or introducing it into matter which it is desiredto treat. Ultrasonic waves are of the nature of sound waves in thattheir energy is reflected and deflected as they strike solid or liquidsurfaces.

Since effective ultrasonic treatment of any nature re-' quiresabsorption of the wave energy, it becomes neces sary to reduce thisreflection as much as possible.

in acoustical design, the reflection of audible sound (echoes) isreduced in a room by making the wall and ceiling surfaces rough anduneven. This contributes to clear or pure sound which retains the samecharacteristics it had when transmitted by the source to the adjoiningmedia. Such sound is not changed by the interference of reflected soundenergy. Rough and elastic surfaces assist in the absorption ofultrasonic energy. Conversely, smooth and solid surfaces reflect thegreater part of this energy. Because of greater elasticity, liquidsabsorb wave energy to a slightly greater extent than solids. Theseprinciples are made use of in the design of the coupling devicedescribed herein. a

By coupling is meant the transfer of wave energy Wh1ch is beingtransmitted through one medium, to waves which are then transmittedthrough another medium. In the device which I will describe, thelongitudinal waves travel downward through air from the fin-air jetinterruption to the upper diaphragm surface. When they strike thediaphragm, which due to its buoyancy on a fluid body is free to vibrate,they will force a resonant vibration upon it. It in turn through itsparts which are in contact with the liquid, transmits this vibrationalenergy or micro-agita- .11;

tion to the molecules of the liquid, causing these molecules to assumewave motion in many directions. latter waves may be called bulk waves,due to their irregular directions of propagation through the medium.Thus the resonator diaphragm acts as a coupling agency, coupling theenergy of the longitudinal air transmitted waves to the energy whichgenerates the bulk waves in the liquid.

The ultrasonic coupling device disclosed in the present case makes useof the ultrasonic wave generator set forth in my Patent No. 2,715,384,issued August 16, 1955, or a similar device. My present ultrasonicenergy coupling device can be used for the treatment of liquids for suchpurposes as sterilization, homogenization, emulsion and the like.

A further object of my invention is'to provide a device of the typedescribed which is simple in construction and is durable and efficientfor the purpose intended.

Other objects and advantages will appear as the specification proceeds.The novel features will be set forth in the claims hereunto appended.

These I 2,832,572 Patented Apr. 29, 1958 Drawings My invention isillustrated in the accompanying drawings, forming a part of thisapplication, and in which:

Figure 1 is a top plan view of the device with a portion being brokenaway to disclose the disc and peripheral fins of the resonator diaphragmassembly;

Figure 2 is a transverse section taken along the line il--li of Figure1;

Figure 3 is a horizontal section taken substantially along the lineIll-11 of Figure 2 and shows a top plan view of one half the upper discwith its perforations, and one half the lower disc with its agitatorrods;

Figure 4 is an enlarged vertical section taken along the line 'iV ofFigure 2, and shows the ring-shaped conduit and nozzle and a portion ofthe disc and one fin of the resonator diaphragm assembly;

Figure 5 is an enlarged transverse section through a portion of Figure 3as indicated by the line V-V; and

Figure 6 is a modified form of the resonator diaphragm assembly.

Description While I have shown only the preferred forms of my invention,it should be understood that various changes, or modifications, may bemade within the scope of the annexed claims, without departing from thespirit thereof.

In carrying out my invention, 1 make use of the ultrasonic devicedisclosed in my Patent No. 2,715,384, above mentioned. The patenteddevice includes a motor A, mounted on a platform B, that in turn issupported by a frame C. The frame C extends above a tank or trough D inwhich a liquid E or other substance, is disposed that is to be treated.If the substance to be treated is in batch form, then a tank D may beused. If the substance can be moved in a continuous manner, such as aflowing liquid, then a trough D would be used. The invention adaptsitself to a batch or continuous process.

The motor A has a motor shaft 1 that extends downwardly through anopening in the platform B, and a disc F is carried by the lower end ofthe motor shaft. Above the disc F, I mount a ring-shaped conduit G, andFigure 2 illustrates how supporting bolts 2 connect the conduit G to theplatform B so that the plane of the ring-shaped conduit G, will parallelthe plane of the disc F. Nozzles G extend downwardly from thering-shaped conduit G, and they communicate with the interior of thering.

The periphery of the disc F has a plurality of radially extending fins Fthat are arranged concentric with the axis of the shaft 1. The circularrow of nozzles G are arranged concentrically with the shaft axis and thenozzle outlets are disposed just above the fins F An air pipe 3communicates with the ring-shaped conduit G, and delivers air underpressure to the conduit. The nozzles G will direct the compressed airdownwardly in streams that are caused to pulsate at ultrasonic frequencyby the fins F as they are moved transversely through the air streams.The disc F will be rotated at. about 3600 R. P. M. and the diameter ofthe disc is about five feet two inches which will give it a peripheralspeed of about 1000 feet per second. There are approximately 1700 finsarranged around the disc periphery and there are about thirty nozzles Galthough far fewer are illustrated in Figure 1 for purposes of clarity.The fins are spaced apart and the streams of air in passing through therecesses provided between the fins, will be interrupted by the fins tocreate about 100,000 or more Waves per second. When 1700 fins F aremounted on a disc rotating 3600 R. P. M., the air stream from one nozzleG will be interrupted 102,000 times per second. With thirty nozzles, thecombined interruptions will be 3,060,000 per second.

The parts thus far described produce tin-air jet interruption atultrasonic frequencies. It is readily understood that the frequency maybe varied by making the diameter of the disc F larger or smaller whilethe fin spacing remains the same. Frequency variation may also beaccomplished by varying the speed of the driving motor A. Recentimprovements in the design of variable speed electric motors will be ofgreat importance to the generation of ultrasonic energy by the deviceset forth in my Patent No. 2,715,384. The intensity of the wave energymay also be varied by changing the pressure of the air which isdelivered by the conduit to the jets. These variations of frequency andintensity are of great value in the development of uses for ultrasonicenergy.

The purpose of the present invention is to take this cylindrical aircurtain pulsating at ultrasonic frequency and deliver the pulsationsinto the body of the matter being treated rather than direct thepulsating medium against the surface of the material to be treated. Itis best now to refer to Figures 2 and 3 where i show a resonatordiaphragm assembly I comprising a hollow ring H and a pair of discs Iand l secured to each other. The upper disc I is made of hard rubber orplastic and has perforations 4 therein, see Figure and the left half ofFigure 3; while the lower disc 3 is made of thin metal with a pluralityof agitator rods K, depending from this plate, see the right half ofFigure 3, and also Figure 5.

Figure 5 illustrates the hollow ring H, the upper and lower discs J andI and the agitating rods K on a larger scale. The upper disc I has aplurality of openings 4 therein. As many openings 4 as possible areprovided in the upper disc I so long as the layer is not weakened. lprefer that the openings 4 be less than in diameter and that they bespaced from each other about Mr" or less on a disc approximately fivefeet two inches in diameter. If a smaller upper disc I is used, theopenings 4 and the distances between them would be reducedproportionately. The upper disc is about /s thick.

The lower disc I of metal is about thick and is preferably bonded to theupper disc so that the two discs will constitute one unit. Figure 5shows the agitator rods K with their upper ends welded or otherwisesecured to the lower disc 1 The agitator rods are about in diameter andare preferably made of stainless steel. The agitator rods are of thesame diameter throughout their length and are spaced about A" apart in adisc having a diameter of 5 2".

The two discs 3 and l are secured together and are mounted on the hollowring H. The cross sectional diameter of the hollow ring is about 3 /2",and the outer surface of the ring has a clearance from the adjacentsurface of the vat or trough D, of about /s". The hollow ring H floatson the surface of the liquid E and the depth of the liquid is about 4 to6". The agitator rods K are 4" or 5" long and they will thereforepenetrate a distance of /2 to 1%" into the liquid. I do not wish to beconfined to these exact measurements.

My device as described thus far consistsof the resonator diaphragmassembly I that floats above the surface of the liquid B being treated,due to the buoyancy of the hollow ring El that supports the discs I andJ adjacent to their peripheries. The discs are concentric to the hollowring 1-1. When treating liquids E of low specific gravity, additionalsupport for the disc may be required beside that provided by the buoyantforce of the displaced liquid on the hollow ring H. In Figure 2, Iillustrate that the resonator diaphragm assembly may be additionallysupported by sensitive helical springs L so arranged that the .totalsupporting force due to buoyancy and pension will permit free vibrationof the assembly .l. The lower ends of the coil springs L are connectedto the upper disc 3 while the upper ends are connected to brackets 5which in turn are secured to the frame C.

From the foregoing description of the various parts of device, theoperation thereof may be readily understood. The tank or trough Dcontains the fluid to be treated and the agitator rods K will penetratethe liquid to the proper depth. The motor A is started and the disc Pwill be rotated at the desired speed. Compressed air or other desiredgas will be fed into the ring-shaped conduit G and the nozzles G willdeliver the air in streams that will pass downwardly and be interceptedby the fins P so that the air will be vibrating or pulsating atultrasonic speed.

The cylinder of pulsating ultrasonic wave energy will strike the upperperforated disc I of the resonator diaphragm assembly 1. Due to theuneven upper surface of the upper disc I caused by the multitude ofopenings 4, and due to the elastic support of the two discs I and i bythe hollow ring H and the coiled springs L, the resonator diaphragmassembly will absorb a great part of the energy produced by thepulsating curtain of air striking it. The uneven top of the upper disc Iconstitutes an absorbent cover for the resonator diaphragm assembly J,and absorbs the ultrasonic energy waves from the generator. The upperand lower discs will therefore vibrate in resonance at the ultrasonicwave frequency of the generator which comprises the air jets from thenozzles G and the pulsating device which consists of the rapidly movingdisc fins F and the spaces between the fins. These vibrations and theiraccompanying energy are transmitted to the desired depths in the liquidE, by the agitator rods K, and to some extent by the hollow ring Hitself that rests on the surface of the liquid.

At this point I should like to describe the characteris tic of soundknown as resonance and show its relation to the principle underlying myinvention. Two or more vibrating bodies are said to have resonantvibration when they are vibrating at the same frequency. The naturalfrequency of a body is the frequency at which it vibrates freely withoutsignificant interference from other vibrations. This natural frequencydepends on its weight, shape, material, and position or attachment. Avibrating body may force its own vibrational frequency on surroundingbodies, in which case they are said to be vibrating in forced resonance.A common example of resonance in audible sound is that of a listener ina house in which all doors, windows, and other openings are closed. Thewalls are of brick or other rigid material and the roof is of tile orshingles heavy enough to reflect or absorb sound energy. Doors andwindows are of normal construction. Sounds of fairly high intensity fromthe outside, such as ambulance sirens, loud talking, dogs barking andthe like are readily heard and identified by the listener. The soundenergy which travelled from the various sources and struck the solidwalls or roof was either absorbed or reflected. At the same time thesound waves which struck the doors and window panes were able to induceor force their vibrational frequencies into these parts. The innersurfaces of these vibrating bodies generated sound waves in the airinside the house which were carried to the ear of the listener.Obviously there is some energy lost at each of these thin structuralmembers due to their rigidity and framing. If we disregard this loss wemay say that the outside sound waves, the thin member (door or window)and the inside sound waves have a resonant frequency. The same principleof resonance applies to ultrasonic energy waves. The resonator diaphragmassembly of my invention is for the purpose of transferring ultrasonicwave energy from air to liquid thus avoiding the interface reflectionloss.

My resonator diaphragm assembly I with its agitator rods K thatpenetrate the liquid E, provide novel means for getting the ultrasonicvibrations beneath the reflecting surface of the liquid or other matterbeing treated. There is no true coupling effect if the vibrations aresolely directed against the surface of the liquid because some of suchvibrations will be reflected from the surface. The resonator diaphragmassembly I in my device when vibrated by the ultrasonic energy willtransfer this energy into the body of the liquid with little lossthrough reflection, because the agitator rods K penetrate the liquid.The openings 4 in the upper disc J are closed by the lower disc J andthe uneven top surface of the upper disc will receive more vibrationsthan if the top surface were smooth.

The hollow ring H may be of any desired size and need not be of circularcross section. In fact the resonator diaphragm assembly I might be madea hollow metal disc M, see Figure 6, and thus do away with the hollowring H. The top of the hollow disc M could have the plastic perforatedlayer M secured thereto and the agitator rods M could extend downwardlyfrom the bottom 11 of the hollow disc. The ultimate design for theresonator diaphragm assembly I or the hollow disc M is to provide onehaving the same natural frequency as the generated waves. The upper andlower discs J and J or the hollow disc M would then vibrate in naturalresonance with the generators vibrations. The plastic top layer M wouldhave perforations 12 therein.

I claim:

1. In a wave energy coupling device for ultrasonic energy: means forproducing ultrasonic waves in an air stream; a member having a surfacesubstantially no-nreflecting to ultrasonic waves and being positioned tothe ultrasonic air stream so as to receive and vibrate in unison withthe ultrasonic Waves; means containing a 1nedium to be treated; Saidmember carrying agitator rods that extend into said medium; whereby theultrasonic waves are introduced into the interior of the medium withsubstantially no reflection of the waves from the surface of the medium.

2. The combination as set forth in claim 1: and in which thenon-reflecting surface of the member has a plurality of recesses to makethe surface rough and therefore substantially non-reflecting toultrasonic waves.

3. The combination as set forth in claim 1: and in which buoyant meansfloats on the medium to be treated and supports the member in a positionpermitting the agitator rods to penetrate the medium.

4. The combination as set forth invclaim 3: and in which coil springsprovide an auxiliary-yielding support for said member in addition to thebuoyant means.

5. In a wave energy coupling device for ultrasonic energy: means forproducing ultrasonic waves in an air stream; a resonator diaphragmassembly having an upper and a lower disc in contact with each other;the upper disc having a plurality of openings therein providing asurface substantially non-reflecting to ultrasonic waves; a plurality ofagitator rods depending from the lower disc; means containing a mediumto be treated, the me dium being penetrated by the rods; the upper discbeing positioned in the ultrasonic air stream so as to receive andvibrate in unison with the ultrasonic waves; whereby the lower disc androds will also vibrate in unison with the ultrasonic waves fortransferring the energy of the waves into the interior of the materialto be treated with substantially no loss of ultrasonic energy fromsurface reflection of the medium being treated.

6. The combination as set forth in claim 5: and in which buoyant meansis connected to the discs and floats on the medium to be treated;whereby the discs are supported clear of the medium and determine theextent at which the agitator rods penetrate the medium.

References Cited in the file of this patent UNITED STATES PATENTS2,068,099 Engle Jan. 19, 1937 2,071,260 Holden Feb. 16, 1937 2,608,391Seavey et at. Aug- 26, 1952 2,693,943 Fowle Nov. 9, 1954 2,715,384 MengAug. 16, 1955

